The present invention is directed to a new and useful film. Films, and especially heat shrinkable films are well known for many packaging applications.
An example is BDF-2050 film supplied commercially by W. R. Grace. This film has proven lo be very useful in packaging applications where high shrink, good optics, oxygen barrier and other desirable features of the packaging film are needed. Film of this type is disclosed e.g. in U.S. Pat. No. 5,004,647 to Shah, incorporated herein by reference in its entirety.
Another example is a film, LID1050, useful in lidding applications. Film of this type is disclosed e.g. in EP 0692374, incorporated herein by reference in its entirety.
It would be desirable to use films, especially heat shrinkable materials like BDF-2050 in end use applications requiring very good heat sealability. For example, in uses where a foamed polystyrene tray is loaded with a food product and then overwrapped, impulse sealing is often used. Equipment such as Ilapak, Ossid, and Rose Forgrove systems are used in such applications. Some of these systems are high speed, producing packages at speeds of up to 100 ppm (parts or packages per minute). This use requires a film with good heat sealing properties, especially hot tack strength. Since hot tack strength is related to the flowability of the film material under heat and pressure, and in particular the flowability of the sealant layer of the film, it is important that the film flow and fuse together quickly under sealing conditions so that reliable heat seals can be made consistently at relatively high speeds.
For lidding on foam trays, toughness as measured by a low percentage of abuse failures (cuts) is required. For uses where a polyester or aluminum coated tray is loaded with a food product and then overwrapped with a film, cuts in the tray edges can occur during packaging and distribution. Impulse sealing is used for this type of overwrapping also. Thus, in this end-use application, a combination of good sealing and toughness is needed.